Deal likely unlocks the most funding for roads, bridges and ports in decades that will help stimulate the country's economy.
US President Joe Biden has embraced a bipartisan Senate deal to spend hundreds of billions of dollars on infrastructure projects, building roads, bridges and highways and helping stimulate the economy.
"We have a deal," Biden told reporters on Thursday, flanked by Democratic and Republican senators who wrote the $1.2 trillion, eight-year proposal.
One of the members of the Group of 21 senators, Republican Rob Portman said, "We didn’t get everything we wanted but we came up with a good compromise."
He said they had commitments from Republicans and Democrats alike to get this thing "across the finish line."
Senate Republican Leader Mitch McConnell, who was briefed on the G-21 plan early on Thursday, would not yet say whether he will back the initiative.
Republican Senator Mitt Romney said details would be released later in the day.
Lawmakers will be looking closely at how the proposal pays for around $559 billion in new spending contained in the package.
After months of sometimes difficult negotiations between the White House and lawmakers, Democratic and Republican members of the group displayed high spirits, chuckling and smiling together at microphones in the driveway of the White House.
Before the White House meeting, Portman told reporters on Capitol Hill that McConnell "remains open-minded and he's listening."
Portman, a leading Republican member of the G-21, added, "He hasn't made his decision."
Democrats, who hold narrow control of both chambers of Congress, want to pass a bipartisan bill but also push through another large-scale spending package over Republican opposition using a Senate maneuver called reconciliation.
For Biden, securing a large-scale infrastructure package is a top domestic priority.
Democratic Senate Majority Leader Chuck Schumer said on Thursday he was "encouraged" by what he had heard of the proposal, though he cautioned that neither he nor House of Representatives Speaker Nancy Pelosi, also a Democrat, had seen it.
Schumer also said a $1.2 trillion bill focused on physical infrastructure would not get the Democratic votes needed to pass it without an accompanying package tackling social issues, including home healthcare.
"All parties understand, we won't get enough votes to pass either, unless we have enough votes to pass both," Schumer said on the Senate floor. He said the Senate would aim for a vote on the bipartisan plan next month.
A major sticking point had been how to pay for the investments. Biden has pledged not to increase taxes on Americans earning less than $400,000 a year, while Republicans are determined to protect a 2017 cut in corporate taxes.